Received August 15, 2019; Revised August 20, 2019; Accepted August 21, 2019.

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Abstract

Biochemical changes of CaMsrB2 expressing transgenic rice seed during germination in heavy metal stress condition were studied. Transgenic lines, L-8 (single copy) and L-23 (two copy), along with WT were evaluated under metal stress conditions. All the plants were treated with different metals and their two selected concentration. Final germination rate, changes in amylase activity, total protein, reducing and total sugar was observed in all treated and control samples. Metal stress showed considerable impact on final germination rate in CaMsrB2 expressing transgenic rice seed. Application of lead salt showed 100% germination in L-23 compared to Zn and Cu. However, maximum germination rate was recorded in L-23 seed when it was treated with 4 mM PbCl2 and 0.5 mM CuCl2 compared to WT. Amylase activity and total reducing sugar was increased in transgenic rice seed treated with 2 mM and 4 mM PbCl2 as compared to WT. L-23 showed substantial increase in amylase activity and total reducing sugar compared to L-8 and WT. However, transgenic seeds treated with Zn and Cu showed substantial decreased in amylase activity and total reducing sugar with few exceptions. L-23 performed well regarding amylase activity and total reducing sugars in metal stress condition particularly in Pb as compared to Cu and Zn. CaMsrB2 expressing transgenic seed germination and their carbohydrate metabolism under metal stress condition were discussed. It was evident from the data that PbCl2 showed better germination rate due to enhance amylase activity and carbohydrate mobilization of CaMsrB2 expressing transgenic seed as compared to Cu and Zn.